Australia: The Land Where Time Began

A biography of the Australian continent 

In large areas of boreal conifer forests this is the most important type fungal symbionts, and associated with some very large canopy trees in tropical rainforest. It is most common in areas where the main nutrient deficiency is nitrogen. The fungi absorb ammonia, as well as some nitrate. They can also access organic nitrogen in the soil. They also uptake phosphate in some habitats. Most commonly they are found on trees of the families Betulaceae, Pinaceae, Fagaceae, Dipterocarpaceae, Leguminaceae and Myrtaceae.

The basidiomycetes are the fungal type most commonly forming this type of mycorrhiza. These are often used as food, cepes, truffles and chanterrelles. Instead of the usual internal life style, where the fungi penetrate cells walls, their extensively branched hyphae penetrate between the cell walls, the resulting network of hyphae being called a Hartig net. This net provides a very large surface area for transference of nutrients. On the surface of the lateral roots, the fungus forms a dense mat of hyphae that isolate the root from the soil, making the plant entirely depended on the fungus for its nutrients. The mycelium extends metres into the soil around the roots to form an efficient nutrient collecting network. Evidence has been found that the fungus can cause weathering of some minerals. The mycelium of this type of association can spread over many hectares, infecting several trees.

Sources & Further reading

1. Mary E. White, Earth Alive, From Microbes to a Living Planet, Rosenberg Publishing Pty. Ltd., 2003

• Arbuscular Mycorrhizas
• Ectomycorrhizas
• Ericoid Mycorrhizas
• Orchid Mycorrhizas